High-frequency apparatus for medical purposes



Nov. 23, 1954 G. TOUZEL 2,695,021

HIGH-FREQUENCY APPARATUS FoR' MEDICAL PURPOSES 'Filed Nov. 30, 1949 v 2 Sheets-Sheet l Alf (250v) f AGE/V75 Nov. 23, 1954 G. TOUZEL HIGH-FREQUENCY APPARATUS FOR MEDICAL PURPOSES Filed Nov. 50,1949

2 Sheets-Sheet 2 INVENTUR 650F655 75a ZEL BY MW u w a.

United States Patent O HIGH-FREQUENCY APPARATUS FOR IVIEDICAL PURPOSES Georges Touzel, Bordeaux, France Application November 30, 1949, Serial No. 130,334 Claims priority, application France December 9, 1948 6 Claims. (Cl. 128-1721) The present invention relates to improvements to methods and apparatus for generating and applying high frequency current, more especially for medical purposes.

It consists chiefly in generating high frequency currents, in particular of a frequency ranging from 3 to 30 megacycles, and in rectifying it in such manner as to leave only current impulses of the same directions, these impulses being, in particular, used to obtain analgesia or anaesthesia, or other therapeutic operations.

Other features of my invention will appear from the following detailed description thereof, with reference to the accompanying drawings, given merely by way of example, and in which:

Fig. 1 is a diagrammatic view of an apparatus according to my invention;

Fig. 2 is a view showing separately a device for controlling the variable coupling means included in this apparatus.

I make use, according to the invention, or rectified high f1 equency currents, which are applied to the patient or to the tissues to be treated, by means of suitable elec trodes, the high frequency that is considered ranging, for instance, substantially from 3 to 30 megacycles, although these limits can be exceeded at either end of the range, in particular into the range of hyperfrequencies.

The use of these rectified high frequency currents, instead of the low frequency currents known in the prior art, and especially when said currents are rectified as hereinafter described, gave surprising results in the field of application that is considered. They are much better tolerated by the patient, in particular in iontophoresis, i. e. when said currents are applied to produce electrolysis in situ; it is found that the beginning of pain is delayed while making it possible to use higher current intensities.

It was found, according to the present invention, that by applying the positive terminal to the part to be insensibilized, both in dentistry and in pure medicine, remarkable anaesthetic or analgesic results were obtained. Thus, it becomes possible to perform indolorous milling of the teeth; likewise, in pure medicine, remission of the pain can be obtained in many cases, same as quick healing of post-traumatic elfects (sprains, strains, etc.).

Concerning first the source of high frequency current, many kinds of apparatus can of course be used. However, it seems advantageous to make use of the arrangement illustrated by Fig. 1, which includes two pentodes V1 and V2 coupled in parallel to constitute an electron coupled oscillator unit. The pentode V1 includes a cathode 201, an earthed or grounded cathode heater 211,"a control grid 251, a screen grid 261, an earthed suppressor grid 291, and a plate or anode 301. Similarly, the pentode V2 includes a cathode 202, an earthed cathode heater 212, a control grid 252, a screen grid 262, an earthed suppressor grid 292, and a plate or anode 302.

The two control grids 251 and 252 of these tubes are connected together through a self inductance coil L with a central tapping, the middle point of this coil L being connected through condenser 32 with oscillating circuit L1C1, tuned to the frequency to be transmitted (for instance 13.66 megacycles). Grid bias is obtained by means of a resistor 31 inserted between said middle point of coil L and the ground so that the voltage drop across said resistor 31 will supply the necessary negative bias. The screengrids 261 and 262 are connected together by a conductor 27 a point 28 of which is connected to the H. T. voltage supply through a resistor R2, so that the screen grid current at this point 28, flowing through R2, causes a voltage drop to voltage (250 v.) to a voltage of volts. A by-pass condenser C5 acts as a short-circuit for the high frequency so that the screen grids 261 and 262 are at ground potential for radio frequency voltage. The suppressor grids 291 and 292 are earthed.

The two plates 301 and 302 are connected together through a self inductance coil L the middle point of which is connected to a second tuning circuit L2C2 (of the same oscillation frequency at Llcl). A choke coil SC is inserted between the H. T. supply and one end of coil L2.

The two coils L and L act as traps for parasitic oscillations to prevent tubes V1 and V2 from acting on each other in an undesirable fashion.

The oscillations obtained at the output of this oscillator unit are made to act upon a rectifier device which may be of any suitable type (diode, grid-cathode space of a triode, pentode, etc., or contact type rectifier, in particular making use of germanium or silicium), but which is preferably arranged in such manner as to connect with the earth, and therefore to suppress, every second half alternation, Whereas the other ones are allowed to remain, being eventually transformed in such manner as to be in the form of the impulses P shown by Fig. 1.

Thus, according to the embodiment illustrated in Fig. 1, the oscillations are received in a tuning circuit L3C3 tuned to the oscillator frequency and are applied to a rectifying device in the form of a pentode tube RE, which actually corresponds, insofar as the rectifying action is concerned, to a diode rectifier. The pentode tube RE comprises a cathode heater 32, an earthed cathode 34, a control grid 33, a screen grid 35, a suppressor grid 36, and a plate or anode 37. The oscillations received in the circuit L3C3 are applied to the grid 33. In these conditions, every positive half alternation passes through the tube from grid 33 to cathode 34 and, flowing to the earth, is thus eliminated. The negative half alternations remain, giving impulses P the form of which depends upon the characteristics of the circuits-in particular upon the resistance R hereinafter mentioned, which advantageously should be highand upon the grid bias.

Advantageously, a filter device is provided to stop the residual nonrectified parasitic high frequency oscillations, this filter including, for instance, inserted between one end of coil L3 and the ground, a choke coil S1C1, a resistor R (which may be variable) and by-pass condensers C.

The electrodes to be ble at ElEZ. The electrode to be applied to the part to be treated will preferably be the positive electrode.

Of course, means should be provided to act at will upon the characteristics of the rectified high frequency current, in particular upon its intensity, which means may consist of a variable inductive coupling between the generator proper and the tuning circuit LaCa of the rectifier; however, this coupling might be of another kind, for instance it might act through capacity or any other device.

In the case of inductive coupling, I make use, for instance, of a fixed coil B1 of some turns having a close coupling with L2, connected through a low impedance flexible line, with a similar coil B2 acting upon L3, but movable by means of a control knob K.

By operating this knob, the mutual coupling coefiicient is varied, and therefore the value of the induced current. This current is of the same frequency as that of the generator, since circuit L3C3 is tuned to this frequency.

But it should be noted that the electric coupling, when coil B2 is displaced, varies in accordance with the square of the distance, which gives an exponential variation.

Advantageously and in order to permit an adjustment as gradual as possible, for all positions, I interpose, between control knob K and coil B, means capable of achieving a movement the law of which is the reverse of that above mentioned, whereby, finally, the displacement of said knob can vary in substantially linear relation to the variation of the induced current.

occur from the H. T. supply.

applied to the patient M are visithe effect of a variable For instance said means are constituted by a cam such asthat of Fig; 2.

This device includes a cam 20 operable by means of knob K and adapted to act upon a lever 21 rigid with an arm 22 which carries coil B2. It will be seen that the cam can move through an angle of about 180 whereas the coilmoves only through about 90. Furthermore, close to the position of maximum coupling, the reduc tion ratio increases considerably. Any other system might be imagined.-

One. might possibly provide for at least two reduction ratios, so as to make it possible to' obtain amicrometric adjustment.

The" above system will be further completed, according to another feature of my invention, by means for using, when so desired, nonrectified high frequency current (current- S, Fig. 1), in particular for the electric bistoury. Fig. 1 shows that said currents may be collected across the terminals mm of resonating circuit L303.

Itwill' be of interest to provide means for obviating the parasitic influences that would tend to be introduced by the bistoury and its circuits and which would be of a nature to perturb tuning, therefore to reduce the intensity in circuit LsCs. These means will consist for instance in making. condenser C3 variable, so as thus to ensure, for a suitable adjustment, the maximum output.

The Whole of. the apparatus will be wholly screened, the screeningbeing earthe'd to avoid radiation.

I thus obtain a system which makes it possible to carry out the above mentioned therapeutic operations, in particular:

Anaesthesia or analgesia, or all other therapeutic applications (iontophoresis, cataphoresis, etc.) by means of rectified high frequency current (impulses P),

Sterilization or any other applications making use of iontophoresis,

Other operations requiring nonrectified current (S), in particular electric bistoury operations, diathermia, etc.

In all cases, it will be possible to adjust the utilization current in suitable manner, for instance either by means of adjustable coupling. knob K, or by means of resistance R or of condenser C3, etc.

Of course, means are to be provided to observe this current, so as to permit of measuring the therapeutic action, since the doses are variable according to the im-- portance and the nature of the lesion to be treated.

Thus, in the case of iontophoresis, itis known that human tissue behaves in the same manner as an aqueous electrolyte. The insertion of the negative electrode in a natural or artificial cavity of the tissue, the positive electrode being in contact with another part of the patient, causes water to be dissociated into two elements H and O. The therapeutic action is measured in decicoulombs. Therefore, ifthe intensities I are read in amperes on a milliammeter such as MA (Fig. l) and if the time t is measured, product It can be measured and dosed.

But, actually, it is impossible to determine I "a priori because the value to be adopted depends upon the tolerance of the patient. Furthermore, I varies between the beginning and the end of the operation, due to habit acquired by the patient which permits of gradually increasing I.

It is therefore preferable to provide means for integrating product Ldt. But, on the other hand, there must be a certainty that electrolysis truly takes place, since electrolysis starts only for a potential difference between the electrodes higher than a minimum value.

In order to overcome these difliculties, I achieve, according to another feature of the invention, a true electrolytic counting by means of a kind of voltameter such as shown at V in Fig. 1, i. e. an apparatus which measures ions.

This apparatus, which is for instance inserted in series between ammeter MA and the earth, includes a U-shaped tube 1 containing an electrolyte, for instance a solution of soda (NaOH) in the proportion of 1/50. Branch B further contains a small amount of suitably colored petroleum 4 and it is connected at the top with a capillary tube 5 in communication with a bulb 6 open at 7 into the atmosphere. This tube cooperates with a graduated scale 8 which, in order to adapt the zero to every particular case, can be moved by means of a rack and pinion or other equivalent device controlled, for instance, through a knob 9.

In branch 3, two electrodes 10 and 11, one in particular of electrolytic iron, are provided, one of these electrodes being connected with the ammeter and the other with the earth. Furthermore, the free space above the liquid is in communication with the outside through a valve 12 operable at 13 against the action of a spring 14 which tends to keep it closed.

This system works as follows:

While current is flowing, and if the conditions for achieving electrolysis are complied with, the O and H gases evolved by electrolysis accumulate at the top of branch 3, where they exert an increasing pressure, which tends to push up the liquid and petroleum in branch 2, and also in tube 5. The displacement of the level in this tube therefore measures, if scale 8 is suitably marked, the number of decicoulombs corresponding to actual electrolysis, i. e. the amount of ions brought into play.

The scale is marked, for instance, by comparison with a silver nitrate voltameter.

The purpose of bulb 6 is to eliminate the risk of the liquid being spilled out if the apparatus is' kept in action for a long time, for instance due to an accidental shortcircuiting of the electrodes or due to a treatment which is to last for a relatively long time but for which the amount of decicoulombs need not be predetermined. The electrodes are clear from the electrolyte before the bulb is filled.

A layer of an oil having a very high flash point may be provided at the surface of the electrolyte, in branch 3, in order to avoid inflammation of the mixture in the case of the eelctrodes being cleared on after the other, as a spark might otherwise, in this case, ignite the mixture of hydrogen and oxygen.

It should be noted that this counting method measures only the amounts of current used to produce iontophoretic phenomena.

I may provide a device for disconnecting the counter for treatments that exceed the total range of the scale and for which the amount of current per minute can be predetermined. The indications supplied by milliammeter MA, the intensity remaining constant, are then suificient. Such a disconnecting device is shown in Fig. 1 in the form of a by-pass contact 23.

My invention makes it possible to perform various therapeutic operations as above mentioned in improved conditions, in particular concerning the patient, who better supports these operations, and with the possibility of a very high precision.

In a general manner, while I have, in the above description, disclosed what I deem to be practical and efficient embodiments of my invention, it should be well understood that I do not wish to be limited thereto as there might be changes made in the arrangement, disposition and form of the parts without departing from the principle of the present invention as comprehended within the scope of the accompanying claims.

What I claim is:

1. An electric treatment apparatus which comprises, in combination, a generator of electric current of a frequency' ranging from 3 to 30 megacycles, a circuit including two contact electrodes for application to the patient, means coupling said circuit with said generator, said means including rectifying means for changing the alternating current from said generator into a succession of current impulses all of the same sign flowing through said electrode circuit, said current impulses being fed to said contact electrodes.

2. An apparatus according to claim 1, in which said rectifying means includes a multi-electrode rectifier having one electrode connected to one side of a parallel resonant circuit and another electrode connected to ground, one of. said contact electrodes being connected to the other side of said parallel resonant circuit and the other of said contact electrodes being connected to ground whereby every second half alternation of the alternating current in the parallel resonant circuit is grounded.

3. An electric treatment apparatus which comprises, in combination, a generator of electric current of a frequency ranging from 3 to 30 megacycles including an output circuit, said output circuit including a parallel resonant circuit, a utilization circuit including a parallel resonant circuit tuned to the frequency of the parallel resonant circuit of said output circuit and a rectifier circuit, said utilization circuit having two contact electrodes for application to the patient, and means adjustably coupling said utilization circuit with said generator output circuit.

4. An electric treatment apparatus Which comprises, in combination, a generator of electric current of a frequency ranging from 3 to 30 megacycles including an output circuit, said output circuit including a parallel resonant circuit, a utilization circuit including a parallel resonant circuit tuned to the frequency of the parallel resonant circuit of said output circuit and a rectifier circuit, said rectifier circuit changing the alternating current from said generator into a succession of current impulses all of the same sign flowing through said utilization circuit, two contact electrodes connected in said utilization circuit for application to the patient, one of intended to be applied on the patients part to be treated, means for adjustably coupling with said generator circuit, filter means for stopping residual non-rectified high frequency current and a high resistance interposed between said utilization circuit and the last-mentioned electrode 5. An electric treatment apparatus according to claim 4, further including terminals connected across a portion of said utilization circuit for collecting non-rectified high frequency current from said utilization circuit.

electric treatment apparatus which comprises, in combination, a generator of electric current of a frequency ranging from 3 to 30 megacycles including an output circuit, a rectifying tube, the cathode of which is References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 569,380 Hollingsworth Oct. 13, 1896 1,908,688 Call May 16, 1933 2,263,205 Conrad Nov. 18, 1941 2,311,935 Dobert Feb. 23, 1943 2,448,541 Maxon Sept. 7, 1948 2,465,838 Bernard Mar. 29, 1949 FOREIGN PATENTS Number Country Date 858,688 France May 20, 1940 OTHER REFERENCES Radio Amateurs Handbook for 1948, 25th edition.

Copyrighted December 1947; page 109.

Journal of the American Medical Association for Januuary 7, 1950, page 27. (Copy in Scientific Library.) 

